Title

Resolved Hubble Space Spectroscopy Of Ultracool Binary Systems

Keywords

Galaxy: solar neighbourhood; Stars: binaries: visual; Stars: fundamental parameters; Stars: late-type; Stars: low-mass, brown dwarfs; Techniques: spectroscopic

Abstract

Using the low-resolution mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST), we obtain spectra from 20 spatially-resolved, ultracool dwarfs, eighteen of which belong to nine very low-mass binary systems with known angular separations in the range 0″.37-0″.098. For these dwarfs, we derive their spectral types to be in the range dM7.5 to dL6 by either obtaining their PC3 index value or by comparing our STIS spectra with ground-based spectra of similar spectral resolution from Martín et al. (1999b). We have searched for H α emission in each object, but the emission is clearly detected in only two of them. We find that the distribution of Hα emission in our sample is statistically different from that of single field dwarfs, suggesting an intriguing anti-correlation between chromospheric activity and binarity for M7-M9.5 dwarfs. We provide strength measuments of the main photospheric features. We derive calibrations of spectral subclasses versus F814W and K-band absolute magnitudes for a subset of 10 dwarfs in 5 binaries that have known trigonometric parallaxes. © ESO 2006.

Publication Date

9-1-2006

Publication Title

Astronomy and Astrophysics

Volume

456

Issue

1

Number of Pages

253-259

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1051/0004-6361:20054186

Socpus ID

33748695058 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/33748695058

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